Using a DC-DC Buck/Boost Converter with an input of 8 - 30 V DC, and an output of 12 V DC and maximum of 10 Amps. The generator that is attached to the input of the converter has an efficiency of 72.5% and the converter has an effiency of 85%. The manufacturer states that the converter can output 100 watts continuous and 120 watts peak.

so, with this DC-DC Buck/Boost converter is Vin*Iin*generator efficency=Vout*Iout*converter efficiency?

Wattage out will alway be less than wattage in, always. Wattage is another term for power.

Voltage is a different story, as is current.

If you use 9V to create 12v then the input current has to be a lot larger to make up the wattage difference. It 20V is used to create 12V then the current on the input is a lot less. Generally this only applies to SMPS, because they convert the voltages.

Linear can't boost voltage (without a lot of hassle), so the current in is larger than the current out, and they get rid of the excess power as heat. This is why linear regulators, while they work extremely well, are not always the best way to go.